Understanding how much formula to feed your baby is key to ensuring she gets an adequate amount of nutrition -- without overdoing it. The specific amount of formula that your baby needs is dependent on a number of factors, such as her size, age and the addition of solid foods. Even though there are average calculations to use when deciding how much formula to feed your baby, your little one will let you know if she's had enough or is still hungry, says the American Academy of Pediatrics' HealthyChildren.org website.
Match your baby's age with the average amount of formula that he needs. The AAP recommends 2 to 3 ounces every three to four hours for a newborn who is younger than 1 month. Bump the amount up to 4 ounces every four hours when he reaches 4 weeks of age. The number of ounces will increase to between 6 and 8, four to five times per 24-hour period by 6 months of age.
Add your baby's weight into the equation. Before introducing solid foods to your baby's diet, give her 2.5 ounces for each pound that she currently weighs, according to the website Baby Center. You can continue to use this weight-based calculation for each 24-hour period until she reaches between 4 and 6 months of age.
Make allowances for other factors that may influence how much formula your baby needs. For example, if your baby is going through a growth spurt, he may require slightly more formula. These growth spurts typically occur between these ages: 7 to 14 days, 3 to 6 weeks, and 4 to 6 months, according to the website KidsHealth.
Reduce the number of feedings as your baby starts eating solid foods. This doesn't mean to discontinue her formula feedings. Continue to give her 6- to 8-ounce bottles four to five times daily through your baby's first birthday. After 1 year of age, your pediatrician will likely tell you to make the transition from formula to cow's milk.